Masked duck

The masked duck (Nomonyx dominicus) is a tiny stiff-tailed duck ranging through the tropical Americas.

Masked duck
Adult males, Tobago
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Anseriformes
Family:	Anatidae
Genus:	Nomonyx Ridgway, 1880
Species:	N. dominicus
Binomial name
Nomonyx dominicus (Linnaeus, 1766)
Synonyms
Anas dominica Linnaeus, 1766 Oxyura dominica (Linnaeus, 1766)

Songs and calls Listen to Masked Duck on xeno-canto

Taxonomy

The only member of the genus Nomonyx, it is intermediate between the rather primitive black-headed duck (Heteronetta) and the very apomorphic true stiff-tailed ducks. It is sometimes included with the latter in the genus Oxyura, but the masked ducks are now considered the descendants of a missing link in the Oxyurini evolution, having changed little for millions of years.^[2][3]

Distribution and habitat

They are found from southern Texas and Mexico to South America and also in the Caribbean. Primarily not migratory, masked ducks are reported as very uncommon vagrants in the southernmost United States, along the Mexican border and in Florida. As of 2000, the conservation status for masked ducks in Texas is 3,800 birds.^[4] On April 1, 1962, it was recorded from Lowndes County, Georgia, where it was photographed by Alexander Wetmore.^[5] Masked ducks breed in any freshwater body with marsh vegetation and surrounded by heavy tree cover. They also occur in mangrove swamps.

• 
  Male
• 
  Female

Description

Breeding adult males have a rust-colored body with a black face and mottled wings. Adult females, winter males, and juveniles have a barred brownish gray body, with two horizontal, dark-colored stripes running through the buff-colored face.

Diet

These ducks mainly feed on seeds, roots, stems,^[6] and leaves of aquatic plants. They also eat aquatic insects and crustaceans. They feed by diving. These ducks are usually very secretive, but they are not rare and not considered threatened by the IUCN.^[1]

References

1. BirdLife International (2021). "Nomonyx dominicus". IUCN Red List of Threatened Species. 2021: e.T22679789A137758280. Retrieved 7 March 2023.
2. Livezey, Bradley C. (1986). "A phylogenetic analysis of recent anseriform genera using morphological characters" (PDF). Auk. 103 (4): 737–754. doi:10.1093/auk/103.4.737.
3. McCracken, Kevin G.; Harshman, John; McClellan, David A. & Afton, Alan D. (1999). "Data set incongruence and correlated character evolution: An example of functional convergence in the hind-limbs of stifftail diving ducks". Systematic Biology. 48 (4): 683–714. doi:10.1080/106351599259979. PMID 12066296.
4. Jack Eitniear (2000). "Masked duck". The Texas Breeding Bird Atlas. Retrieved March 28, 2015.
5. "Masked Duck, Nomonyx dominicus". River Basin Center/University of Georgia. Archived from the original on April 2, 2015. Retrieved March 28, 2015.
6. "Nomonyx dominicus (Masked Duck)" (PDF). The Online Guide to the Animals of Trinidad and Tobago. UWI.

Further reading

• del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (eds.) (1992): Handbook of Birds of the World (Volume 1: Ostrich to Ducks). Lynx Edicions, Barcelona. ISBN 84-87334-10-5
• National Geographic Society (2002): Field Guide to the Birds of North America. National Geographic, Washington DC. ISBN 0-7922-6877-6
• Sibley, David Allen (2000): The Sibley Guide to Birds. Alfred A. Knopf, New York. ISBN 0-679-45122-6